yea the 1156 is a single fillament and the 1157 is a double, I meant the contacts on the bottom of the bulb. I had the same problem as you. For some reason some bulb sockets use a 1156 or 1157 with a single contact on the bottom and some use a double. I don't know why, but I know chrysler uses a double, I had accidently got a single contact and it took me a minute to figure out what was wrong. I have them in my car and they are just as bright as the old style bulb from the side but much brighter in the front.